Still didn't find the link but I did stumble across this when looking at the MT Baja Boss AT's - the last line says 3pms up to 315 width.
I would suggest that you not spend too much effort obsessing over the 3PMSF rating, it truly doesn't make or break the absolute quality or abilities of a tire during true winter conditions.
The 3PMSF rating is a minimal standard and is a comparison to an all-season radial which is absolute garbage for performance during the true winter conditions that you or I experience for about 4-5 months of the year.
The 3PMSF rating is for straight-line acceleration on medium-packed snow with zero consideration for cornering or braking. With no cornering or braking, how can this even be considered remotely important?
Also, the tire industry is self-regulating to maintain this standard and they're not required to test every size of a specific product line.
Certain manufacturers may choose to not rate their wider tires because if they ever get caught falsely qualifying a tire that doesn't meet the criteria of the 3PMSF, they could face massive & costly recalls and potential litigation from consumers and NHTSA etc.
I would put more value in reading user reviews on sites like this forum than using the tire industry's self-proclaimed qualification of 3PMSF.
And, all tire manufacturers have a marketing department to make pretty and alluring performance ads to tempt you further.
YMMV
Some good reading on the subject.
[URL unfurl="true"]https://www.moderntiredealer.com/retail/article/33001713/is-3peak-mountain-snowflake-the-ultimate-in-winter-tire-certification
Remember to remain objective and keep in mind, that these comments are from tire industry executives and have been carefully crafted to convey the message that they are the good guys and doing a great job for your safety.
Some of the comments look pretty shady to me but the general consensus is that the 3PMSF rating isn't that great of an indicator for real and true winter driving.
If you're serious about safe winter driving, buy a snow tire. If a snow tire isn't suitable for your requirements, research and find out what people are successfully using in similar driving conditions to your own.
Don't trust tire ads and feeble qualifications like the 3PMSF rating to guard your safety or the safety of those important to you.
I copied this comment from the link above because I thought it covered more of the important considerations than some of the others.
Aaron Neumann, product development manager, Nexen Tire America Inc.: A 3PMS marking does not represent maximum winter performance. It is more a minimum. A tire that just meets the 3PMS level is a good step up in winter performance from most all-season tires but has nowhere near the traction and control of a dedicated winter tire.
There are many sub-categories of winter tires that qualify for the 3PMS marking, which I will list here, from best to worst: studded arctic winter tires for Scandinavian countries and far north regions; non-studded Arctic tires for those same regions where studs are banned; ice tires with semi-porous treads; alpine winter tires, which sacrifice a little snow and ice performance for more wet and dry performance for those who venture into the snow only on weekends; and finally, all-season and four-season tires that meet minimum winter performance levels but can be used year-round.
An all-season tire that meets 3PMS is still a remarkable tire in the balance of performance it can deliver and for that reason, they represent the top 10% of the all-season tire market. But the best-dedicated winter tires out there can deliver up to 50% more traction and control on snow and ice. The downside, of course, is that dedicated winter tires do not perform well outside of winter conditions and need to be taken off in the summer.
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